Passing variables to a scripting engine... (like php)

Ok. I already posted a question asking how to pass parameters to php.exe when running it directly from the command prompt. However, i've noticed the matter is a bit more complex than i had thought. I will reformulate my question: How the h--- does any Web Server passes information like the URL being processed, posted variables, etc, etc, to a scripting engine??? I've noticed it is not through command line arguments... Could it be using enviroment variables...? The initial purpose of this was to schedule a script to be executed on a periodic basis... but know I am very curious!! Still, i will greatly appreciate workarounds. THANKS A LOT AGAIN. Cheers, Diego.